Railway signaling system.



L. H. THULLEN.

PATENTED NOV. 27, 1906.

RAILWAY SIGNALING SYSTEM.

APPLICATION FILED MAY 22. 1905.

8 SHEETS-SHEET 1.

No. 837,154. 4 PATE-NTED NOV. 27, 1906. L. H. THULLEN.

RAILWAY SIGNALING-SYSTEM. APPLICATION FILED MAY 22. 1905.

a sums-$113111 s- UNITED snares PATENT OFFICE.

RAILWAY SIGNALING SYSTEM.

No. 837,1 s4.

Specification of Letters Patent.

Patented NOV. 27, 1906.

Application filed May 22,1905. Serial No. 261,509.

To (oil whom it may concern.-

Be it known that 1, Louis Ii. Tnr'rtex, a citizen of the United States of America, re-

siding at Edgewood Park, in the county oi Allegheny and State of Pennsvlvania, have invented or discovered new and useful 1mprov'cnients in Railway Signaling Systc1ns,'of which the following is a specification.

Referring to the drawings, which form a part of this specification, Figure 1 is :1 diagrammatic view of my invention; Fig. l, a diagrammatic view of a second form of generator of pulsating current; Fig. 3, diagrammatic representations on the magnetization of the core of a coil when traversed by both an alternating and a direct current; Fig. 4, a view showing the same thing as Fig. 3 when a pulsating and a direct current are used. Fig. 5 is a representation of the value of a pulsating current that is used so that the combined values of pulsating and direct currents would equal the combined values of the direct and alternating currents; Fig. 6, a view similar to Fig. 4 with the generator of Fig. 2 as the originator of pulsating current; Fig. 7, a diagram showing the value of an alternating current necessary to produce the counter electromotive force shown by the curve a when the core is acted on by direct current; and Fig. 8, a view similar to Fig. 4, showin in dotted lines a'displacement of phase that might exist. I My invention relates to a system of railway signaling which employs an alternating or direct current for driving the railway-va hicle and a pulsating current for the track or signaling current. A pulsating current has a character widely difi'erent from an alternat-' ing or a direct current and can be generated in different ways. It can be produced by such generators as are shown on Figs. 1 or 2, or by the mercury-vapor are, or by other means.

An alternating current has a wave form of sinusoidal character, and each wave length rises and falls between a maximum and a f minimum, one above zero and the other helow it, as shown by the line a, Fig. 3. A pulsating current has an entirely difi'erent wave form, which is shown by the line a, Fig. 4, where the wave form lies wholly on one side of zero. A direct or continuous current is represented by the horizontal dotted lines on Figs. 3 to 8, in which the horizontal lines represent ,diiferent current strength, magnetomotive force, or electromotive force,

case may be.

Referring for the ircscnt to Fig 1, 1, 2, and 3 represent bloclt-scctions of a railway, the rail 4 being in this instance shown as continuous, while the opposite rail is divided into the sections 5, 6, and 7 by insulated joints 8 and 9 or otherwise. However, both rails may be divided into insulated sections, if desired. 10 represents a rotary generator of pulsating current and has the two seg ments 11 and 12 to indicate diagramnm ically that there will be two pulsations at -h revolution of the generator. The two brushes of the generator are respectively connected to the mains 13 and 14', across which are connected the primary coils 15 of the transformers 16, there being one of the latter for each block. The secondaries 17 of the transform! ers are connected across the rails, one end of and the other 'to its respective section of the other rail. 18 represents diagrammatically relays of the motor or other type bridged across the rails of the respective block-sections. These relays are not 0 erative by the vehicle-propulsion current, w iether it be direct or alternating, but only by a pulsating current The relays have the current-closers 19, which control the signals 20 in a wellknown manner. So long as the local circuits in which the signals are located areclosed the signals indicate a clear track; but if this local circuit is for any reason opened the signal in such circuit at once indicates danger. Inductive windings 21. connect the rails at each end of each section; but they may be differently arranged and may be constructed as shown in my application Serial No. 214,744. 22 represents the trolley-wire, third rail, or other means of distributing motive current, which is supplied by the generator 23 of direct or alternating current, one brush being connected to the feeder 22 and the other to the rail 4. 25 represents the vehicle provided with the trolley-pole 26, carrying the trolley27.

The operation is as follows: The generator 10 is supposed to be supplying the trans formers 16 with pulsating current, which the secondaries 17 impress on the rails of the.

relays, causing them to hold their arma-tures so as to close the local circuits, including the signals. This is the condition of each sec tion when there is no train on that section.

as theblock-sections, whence it passes through the the secondary being connected to the rail 4 When, however, a train enters a section, the

" the local circuit is again closed, causing the- 'tance of the magnetic circuit.

trucks short-circuit the relay for that' section, whereupon the local circuit is broken and the signal indicates danger.

As soon as the rails of the section are cleared the transformer-circuit again enters the relays and vsignalto indicate safety. I will now explain the advantages which a pulsating signaling current offers in systems involving the principles of the present invention v If a direct current be impressed on a wind-, ing having an iron core, the latter Will come magnetized to an extent depending, on the'strength of the current and the reluc- If an alternating current be simultaneously impressed upon the winding, the impedance of the winding to the alternating current will be inversely as the total magnetization of the core produced by the combined action of both currents.

Referring to Fig. 3, let the horizontal lines represent'the total magnetizationof an iron core traversed by'a direct'an'd an alternating current.

ofone'thousand magnetic linesof force per square centimeter. The line a represents the value of the magnetization at any point of the cycle when the winding is traversed by Each line represents a density an alternating current only. The dotted horizontal line s'hows the magnetization of the cbreiftraversed by'a direct current of seine 'kn'own' value. The line b shows the [magnetization of the core when the winding is traversed" by both an alternating cprrent. and a direct current.

As will be seen,-t'he value of. the magnetization will reach a high valueat one part of the cyclc'and go down to zero at another part.

In Fig. 4 is shown by'the curve a the mag netization of the 'core, due to'a pulsating current of .the same stren th as the alternatin current in Fig. 3, and the dotted curve the magnetization of the core when the winding also'carries a direct current of the same strength as the direct current in Fig. 3. The

maximum value of the magnetization, withthe combined alternating and direct current, I is eight thousand lines, (see Fig. 3,) whilethe maximum value of the magnetization with his but four thousand lines. 55 "sating and direct currents the maximum the combined pulsating and direct current (See Fig. 4.) Therefore with the combination of the pulmagnetization of the core is far less than with the combined action of the alternating and direct currents. The unit of time on all these curves is measured on the horizontal lines. For instance, the distance from c to a may be considered a unit of time and for convenience in this 1 case may be 'considei'e'd'to equal one second. The value of the magneti- 1 nation, the electromotive force, or thecurrent strength is measured on a perpendicular to said hnes. Therefore the magnetization,

the electromotive .force, or t e current strength at any instant is e ual to thefdistance at that instant on 'sai perpendicular by any common scale.

Referring to Fig. 3, at any one instant, as

at c, the strength of the alternating current, i and therefore the magnetization .therebyon is also at the point of total magnetization from the combined currents.

In Fig. 4 and in practice the direction of the pulsating currentis made to traverse the windings 21 in opposition to the direct cur: rent.

Therefore the total magnetization or.

the current strength is equal to the difference between the direct and the pulsating currents. This is plainly shown by Figs. 4 and 5, in which (1 represents the magnetization due to the pulsating current, the dotted line e the value of the direct current, (in all cases shown constant,) and b the resultant magnetization due to the two currents.

Fig. 5 shows the value of a ulsating ourrent that could be used so that he maximum value of the combined direct andpulsating currents would be equal to the combined maximum value of the direct and alternating currents. This shows that a pulsating current having twice the strength of the alter.

nating current could be used with, the same direct current and still have the total maximum values equah This figure is self-explanatory and needs no further comment.

Fig. 6 shows the characteristic of a pulsating current produced by the. generator 28 of pulsatingcurrent, Fig. 2. In this case the pulsating current attains its maximum value ut once in a revolution, as-the current is produced only when the strip 29 is in contact with a brush. In Figs. 4, 5, and 8 the pulsating current attains its maximum value twice in arevolution. "In Fig. 6 the pulsat ing current is zero for half a revolution; but I do not restrict myself to any particular form of pulsating current or to any means of generating same, as my invention broadly is anyway of using a pulsatin current in connection with a closed trac -circuit of any de scription for trical.

railroads,,both steam andelec- The dotted curves f in Figs. 5 and SshoW the relation of the current and electro'motive force that could exist; but the displacement more or less than shown. .It depends entirely upon the capacity on inductance of the circuit.

By Fig. 7 I show how a high saturation is objectionable in an impedance-coil. In an impedance-coil the counter electromotive force equals the impressed electromotive force. To establish this counter electromotive force, it is a wellknown fact that a certain number of magnetic lines of'force per second must be looped within the winding.

Should the core-become nearly saturated by the direct current, it can then bereadil seen that but few more lines could. be orced through the core by the alternating current and that it would require a strong current to force theselines through the core, as the greater the density of the lines in the core the less the permeability of the iron, and therefore the greater the magnetic reluctance of the magnetic circuit.

In Fig. 7 the dotted line 2 represents the electromotive force necessary; to produce the desired direct current and t e desired magnetization due thereto. In this instance it is shown constant. The curve a shows the value of the counter electromotive force necessary to equal the impressed electromotive-force resistance of the coil being neglected. The curve gshows the value of the alternatin current necessary to produce the counter e ectromotive force shown by the curve a when the core is acted upon by the direct -current. The curve I) shows the magnetization of the core due to thecombined action of the direct and alternating currents. If the magnetization of the core is not carried very high-say to four thousand lines per square inch-the current required to magnetize the core would be quite small and con d be represented by the curve a. The higher the magnetization by the direct current the greater theflow of alternating current when coil is also subjected to an alternating electromotive force, and if the magnetization is carried very high by the direct current the value of the alternating current is therefore nearly infinitely great. As it is desirable to keep the alternatin current at its lowest value, it can be readiI seen that the magnetization ofthe core must be kept quite low, in the vicinity of four thousand I lines er square inch, at ordinary frequencies.

' It is desirable that the inductive bond 21 iarthest from the transformer should take hut'iittle current. In this bond the pulsat ing current traverses the winding in the opposite direction to the direct or propulsion The reason less current is desirable is point is on account of the drop due to inipedc of the rail to current of a ow volta e s it is very possible should exist at the relay end with .a minimumvoltage at the transformer end.

The pulsating current in the inductive former end as the, propulsion-current, and therefore takes more energy; but at .this

bond -is in the same direction at the transpoint the additional energy 1s not objection able, as it is ap lied at a ower voltage than wouldbe possi le with an alternating'current, and the consuming of energy at this point is not objectionab e, can be designed to meet this condition Having described In invention, .1 claim- 1. In railway signa ing wherein a closed track-circuit is normally preserved, the motorreturn current traverses the rails and the track and oar-propulsioncurrents traverse the same inductive devices, means for impressing upon the track-circuit a signal-operating pulsating current and means for impressing upon the motor-circuit a current return of different character. i

2. In railway signaling'wherein a closed track-circuitis normally preserved, the motorreturn current traverses the rails and the track and car-propulsion currents traverse the same inductive devices, means for impressing upon the track-circuit a signal-operating pulsating current and upon the motor-returncircuit a current of different character, and causing the signal and motor-return currents to traverse the inductive device in opposite directions.

3. In a railway signaling system emplo g a closed track-circuit, a generator of pulsating current therefor, a car-propulsion motoroperative by a direct or an alternating current having a track-return, and inductive device traversed by both currents.

4. In a railway signaling system emplo ing a closed track-circuit, a generator of pu sating current therefor, a car-propulsion motor operative by a direct or an alternating current having a trackreturn, and inductive devices traverscd in opposite directions by both currents.

5. In a railway signaling system employing a closed track-circuit, a generator of pulsat- .ing current therefor, a car-propulsion motor operative by a direct or an alternating ourrent having a track-return, lnductive devices and signal-actuating mechanrsni bridged in the rails of each block-section and means for permitting the flow of the return-circuit from one section to an adjacent section.

6. In combination in a signaling system, a closed track-circuit, a source of current pulsating in character, and a signal operative by such current.

7 In combination in a signaling system, a track-crrcurt permanently connected to the rails, means for producing a pulsating current for said circuit, and a signal operative by such current.

8. Incombination-in a signalin system, a

as the apparatus- IIO closed track-circuit, a source of currentfor propelling a car on the track, a sourceof puleating current, and means whereby the signal is controlled bythe latter current.

9. In-a signaling system for electric railways, the combination of a lu-ralityof blocksections, both rails of which are usedvfor the return propu1sion-current,'a track-circuit for each blocksection, a source of pulsating current for each track-circuit, a source of current for prcpelling cars tween adjacent block-sections for permitting the propulsion-current to pass from one blocksection to another, but forming a path of high impedance to the pulsating current.

10. In an electric-railway signaling s stem having a closed track-circuit, a plura ity of block-sections, a sourceof pulsating current for supplying the rails of each section, asignal for each block-section controlled bysaid current, a source of direct current for 3 ropelling 'thecars, and means i for ropulsion-current-to traverse .glock-sections.

1 1. A track-circuit for railw ysignalingsys-e teins comprising'a source of unidirectiona curautomatically-operated means 'between it and the track-rails of the track; circuit for changing one of its characteristics,

rent-supply,

on the track, means be ermittmg the othrails'of the --as7.,1s4.

'-anIi---a translating device responsive-only to the operating-current in the track-rails.

1,3, A track-circuit for railway signaling systems com rising a source of unidirectional responsive to itsoperating-current the track-railsw y '13. A track-circuit for railway signaling systems coring rising a source of unidirectional v current-supp a char'gingcircu i tv for said source, means between it and the-track-rails tional current, and a translating device responsive to the altered current.

systems com rising a source of unidirectional current-supp v connection of the source of supply with the trackrails whereby "its'oharacter' of unidirec' tion is changed, and a "translatingdevice.

Signed at Pittsburgthis 16thday of May,

- LOUIS H.'THULLE N.1 Witnesses: Y 1 WI BARBER, i

ANNA RJBEATTY; I

14. A track-circuit for railway signaling an interrupter located in a for altering a characteristic of the unidireci 

